Disclosed herein are heat sinks, and especially light emitting diode (LED) heat sinks and methods of making and using the same.
Light emitting diodes (LEDs) are currently used as replacements for incandescent light bulbs and fluorescent lamps. LEDs are semiconductor devices that emit incoherent narrow-spectrum light when electrically biased in the forward direction of their PN junctions, and are thus referred to as solid-state lighting devices. The high power LED light devices produce considerable amount of heat, which may cause performance degradation or even damage if the heat is not removed from the LED chips efficiently. In an LED light device, the core is a LED chip mounted on a substrate. A transparent top covering the LED chip serves as a lens for modifying the direction of the emitted light. Although there are many different designs, the major heat dissipation route for the heat produced by the LED chip usually is managed through the base to which the LED chip is mounted or through an additional metal heat sink below the base and then to an outer heat sink.
One approach for dissipating heat for LEDs mounted on a printed circuit board is to use a printed circuit board comprising a metal core as compared to traditional printed circuit boards comprising a dielectric core. While metal core printed circuit boards are effective for dissipating heat, disadvantages are increased costs and processing difficulties. In addition, since there are limitations to the size of metal core printed circuit boards, they are more difficult to incorporate into larger size devices.
Another approach for dissipating heat from LEDs is to attach the LEDs directly to a heat sink using a thermally conductive adhesive or tape. A disadvantage of this approach is that it is a labor-intensive process, resulting in increased costs. In addition, the resulting configuration is subject to high failure rates.
Yet another approach to dissipating heat has LEDs on a front side of the printed circuit board, and a heat sink on the back side of the board. To increase the transfer of heat from the circuit board to the heat sink, the printed circuit board has a plurality of holes extending there through, and a plurality of thermally conductive pads is within the printed circuit board. The pads are of a thermally conductive plating, and each pad is associated with at least one of the holes for conducting heat from each of the leads of the LEDs to one of the pads.
It is further noted that die cast aluminum could be used as a heat sink material for LED applications. However, due to productivity issues and secondary operations such as painting of the die cast material, alternative designs to heat sink systems employing aluminum heat sinks also are being sought.
There is a continual need for simplified LED packages having reduced weight, greater design freedom than the designs discussed above, and/or that enhance productivity.